The exemplary embodiment relates to a system for scheduling of processing jobs. It finds particular application in connection with scheduling print jobs in a printing system comprising a plurality of marking engines and will be described with particular reference thereto. However, it will be appreciated that the embodiment finds application in single marking engine printing systems and in other systems in which multiple jobs are scheduled contemporaneously and in particular, where the character of jobs to be processed may adversely impact the processing components or output of the system.
Electronic printing systems typically employ an input terminal which receives images in digital form and conversion electronics for converting the image to image signals or pixels. The printing system may include a scanner for scanning image-bearing documents or be connected to a computer network which supplies the digital images. The signals are stored and are read out successively to a marking engine for formation of the images and transfer of the images to a print medium, such as paper. Printing systems have been developed which employ multiple marking engines for black, process (or full) color, and custom color (single color or monochrome) printing of selected pages within a print job.
With the demands placed on printing systems increasing, printing systems which maintain high outputs over extended periods are desirable. When multiple jobs are to be sequentially printed, a process known as “job streaming” is commonly implemented. Job streaming is the ability of a printing system to complete successive printing jobs with a minimum of delay time between jobs. A control system associated with the printing system identifies that multiple jobs are waiting in a queue, determines their characteristics, and plans the printing of the jobs in sequence, one job at a time. However, some print jobs, such as those involving heavy weight paper, tend to shift the marking engines away from normal operating conditions. These excursions from the mean can cause productivity losses and/or subsystem performance shortfalls and failures. In conventional printing systems which handle heavy weight paper, for example, the printing system may be configured to allow a recovery time by skipping pitches, i.e., leave a gap between sequentially printed sheets equivalent to one or more sheets, when heavy weight paper is to be printed. This reduces excursions from the mean but may also decrease the productivity of the system.